1. Field of the Invention
The present invention relates to an arrangement structure for a motorcycle ignition switch apparatus, to a frame component subassembly for use in a motorcycle, and to a motorcycle incorporating the described structure. More particularly, the present invention relates to an arrangement structure for a motorcycle ignition switch apparatus which has a high degree of freedom in attaching the ignition switch apparatus, and which is resistant to heat and electrical interference from an engine.
2. Description of the Related Art
Virtually all motorcycles sold today include an ignition switch apparatus, into which a key is inserted to switch vehicle power supply on and off. As an example of a conventional arrangement structure for the ignition switch apparatus, the ignition switch is attached to a main frame section which composes part of a vehicle body frame (refer to, for example, Japanese Utility Model Publication No. Hei 6-38785 (page 2, FIG. 1)).
In the example of an arrangement structure for an ignition switch apparatus of a motorcycle disclosed in the patent document mentioned above, the ignition switch apparatus is attached, through a guide tube, to one side of a main frame section extendingleftwardly and rightwardly rearwards from a head pipe.
Additionally, in recent years, a coded ignition switch apparatus for antitheft use has been developed, having a function of performing authentication with a transponder built into a key, and this type of coded ignition switch is being placed into increasing commercial use. Accordingly, it is possible to attach a coded ignition switch apparatus, which has a function of performing authentication with a transponder built in a key, to a main frame section of a vehicle body frame.
However, such a configuration as just described has the following problems.
Usually, since a main frame section of a motorcycle is formed with a small width, the degree of freedom in attachment of the ignition switch apparatus is limited. Further, since the main frame section is positioned in the proximity of the engine, the ignition switch apparatus is inevitably disposed near the engine, and is likely to be influenced by heat and by electrical noise interference from the engine.